In the manufacture of carbon dioxide snow by flashing liquid carbon dioxide, there is created a mixed flow of carbon dioxide snow and vapor. In most applications, it is desired to separate the snow and vapor in the mixed flow, and numerous devices have been developed to this end. One such device is a cyclone separator which relies upon the combined actions of centrifugal force and gravity for separation of the snow in the mixed flow. Such a device is shown in U.S. Pat. No. 1,546,682 and is well known in the art.
One problem experienced with the use of cyclone separators is that the discharge flow is typically divergent due to the swirling motion imparted to the snow in the separator. The flow from the cyclone separator is cone-shaped and typically defines an included angle of 100.degree.. While a divergent flow is acceptable in some applications, it is unacceptable where it is desired to accurately direct the flow, for example, as into a box packed with meat. In such latter applications, a confined, unidirectional flow is desired to avoid wastage of the formed snow.
Attempts to obtain a non-diverging flow from a cyclone separator have heretofore proved ineffective. Various types of nozzle structures have been employed at the discharge end of the cyclone separator to modify the shape of the discharge. A cylinder has been utilized, for example, to obtain a cylindrical flow from the cyclone separator. However, the length of cylinder required to completely reshape the discharge is so great that snow clogging problems are presented. Similarly, attempts to employ various types of baffle structure to reshape the discharge have met with failure due to snow clogging with resultant blockage of the discharge.
The aforementioned problem becomes particularly acute in high volume applications where, for example, meat boxes requiring five to ten pounds of carbon dioxide snow may be filled at the rate of five boxes per minute. Under such operating conditions, an appreciable loss of snow is unacceptable and downtime created by snow clogging problems simply cannot be tolerated.